3,969 research outputs found
Popularity Evolution of Professional Users on Facebook
Popularity in social media is an important objective for professional users
(e.g. companies, celebrities, and public figures, etc). A simple yet prominent
metric utilized to measure the popularity of a user is the number of fans or
followers she succeed to attract to her page. Popularity is influenced by
several factors which identifying them is an interesting research topic. This
paper aims to understand this phenomenon in social media by exploring the
popularity evolution for professional users in Facebook. To this end, we
implemented a crawler and monitor the popularity evolution trend of 8k most
popular professional users on Facebook over a period of 14 months. The
collected dataset includes around 20 million popularity values and 43 million
posts. We characterized different popularity evolution patterns by clustering
the users temporal number of fans and study them from various perspectives
including their categories and level of activities. Our observations show that
being active and famous correlate positively with the popularity trend
A Facile, Fast, and Low-Cost Method for Fabrication of Micro/Nano-Textured Superhydrophobic Surfaces
Background
Alkyl ketene dimer (AKD) is frequently used in paper industry as an inexpensive sizing agent. The formation of a fractal structure after curing the solidified AKD for an extra-long time (4 - 6 days) results in superhydrophobicity. In this study, a facile and low-cost method was utilized to turn AKD’s surface superhydrophobic in a very short period of time.
Method
We fabricated a superhydrophobic layer by dipping glass and paper substrates in molten AKD and then treating them with ethanol after solidification. The samples were characterized by X-ray diffraction, Scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Confocal laser scanning microscopy, and dynamic contact angle goniometry.
Results
The results show that briefly treating the coatings, obtained from isothermally heated AKD melt at 40°C for 3 min, with ethanol leads to superhydrophobicity with an advancing and receding contact angle of 158.7±1.4° and 156.8±0.9°, respectively. By increasing the melt temperature to 70°C and heating time to 6 h followed by ethanol treatment, the advancing and receding contact angles increased to 163.7±1.3° and 162.6±1.2°, respectively.
Conclusions
This enhancement in superhydrophobicity is due to the formation of entangled irregular micro/nano textures that create air cushions on the surface resulting in droplet state transition from Wenzel to Cassie. In this method, ethanol can be used several times, and the energy consumption becomes very low. Based on the other techniques in this field, our method has eliminated the complex equipment and procedure applied in the fabrication of a superhydrophobic AKD.https://scholarscompass.vcu.edu/gradposters/1072/thumbnail.jp
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